The invention relates generally to the etching of servo tracks on magnetic data storage media. More particularly, the present invention relates to etched servo tracks on magnetic data storage tape, methods of forming the etched servo patterns, and methods of positioning read/write heads using the etched servo tracks.
Servo patterns are used to control movement of read/write heads over magnetic data storage media where the media is provided in the form of a circular disk or a tape. The servo tracks on conventional data storage tapes are provided by magnetically encoding the magnetic coating provided on the substrate of the media.
One problem with magnetic data storage tapes is that, because the servo tracks are magnetically encoded, bulk erasing of the magnetic data storage tapes not only erases the data stored on the tapes, it also erases the servo-tracks. Erasure of the servo tracks renders the tapes useless for data storage purposes because proper positioning of the read/write heads can no longer be ensured.
Furthermore, the magnetically-encoded servo tracks are formed using specialized servo-track writing equipment. Reformatting of the tapes after, e.g., bulk erasing has destroyed the original servo tracks, typically requires use of the same specialized equipment which is not widely available. As a result, magnetic data storage tapes including magnetic servo tracks are typically discarded after bulk erasure has destroyed the magnetic servo tracks.
Another disadvantage of magnetic servo tracks on magnetic data storage tape is that the equipment required to write the magnetic servo patterns is costly and can only operate at relatively low speeds, thereby limiting throughput.
The present invention provides magnetic data storage tape with etched patterns in the tape that are used to provide servo tracks. The present invention also includes methods of providing the servo tracks. The servo tracks formed by etching may be read magnetically by magnetically overwriting a pattern etched into a magnetic coating on the tape, followed by detecting the electromagnetic modulation caused by the servo pattern etched into the magnetic coating. The etched servo pattern may also be read optically in addition to magnetically, with the optical writing occurring simultaneously, sequentially or both simultaneously and sequentially. Whether the servo tracks are read magnetically or magnetically and optically, the electromagnetic and/or electromagnetic/optical modulation caused by the etched pattern can be used to accurately position a read/write head on the tape.
Advantages of the present invention include the ability to provide permanent optical servo tracks. Alternatively, if a magnetic servo track is formed in connection with an etched pattern, the present invention provides the ability to reformat magnetic data storage tapes without specialized equipment. That ability to reformat allows users to bulk erase the magnetic data storage tapes without irreversibly destroying the servo tracks because the tapes can be reformatted by magnetically writing over the etched pattern to restore a magnetically encoded servo track to the tape.
In one aspect, the present invention provides a magnetic data storage tape including a magnetic coating on at least one surface of a substrate and a servo pattern including a plurality of etched regions in the magnetic coating on the tape substrate, the plurality of etched regions being spaced apart along a length of the tape. The tape further includes a magnetic signal written over the portion of the tape containing the servo pattern, wherein the magnetic signal and the servo pattern provide electromagnetic modulation to a magnetic read/write head passed over the servo pattern.
In various embodiments, the magnetic data storage tapes may include one servo pattern or a plurality of servo patterns that are spaced apart across a width of the tape. The tapes may include servo patterns in which at least a portion of the magnetic coating in substantially all of each of the plurality of etched regions is removed. Alternatively, each etched region of the plurality of etched regions may be formed by a plurality of stitches in which at least a portion of the magnetic coating is removed. The servo patterns and magnetic signal may provide electromagnetic modulation that is at least about 10% or higher, more preferably at least about 25% or higher, and even more preferably at least about 50% or higher.
In another aspect, the present invention provides a method of manufacturing magnetic data storage tape by providing a substrate with a magnetic coating on at least one surface and etching a servo pattern in the magnetic coating on the tape. The servo pattern includes a plurality of etched regions in the magnetic coating on the tape, the plurality of etched regions being spaced apart along a length of the tape. The method further includes magnetically writing over the portion of the tape containing the servo pattern, wherein the magnetic signal and the etched servo pattern provide electromagnetic modulation to a magnetic read/write head passed over the servo pattern.
In other embodiments, the methods of the present may include forming a plurality of servo patterns in the magnetic coating, the plurality of servo patterns being spaced apart across a width of the tape. The plurality of servo patterns may be formed simultaneously or sequentially. Formation of the servo pattern may also include removing at least a portion of the magnetic coating in substantially all of each of the plurality of etched regions. Alternatively, the etched regions may be formed from a plurality of stitches, wherein at least a portion of the magnetic coating in each of the stitches is removed. The servo patterns and magnetization may provide electromagnetic modulation that is at least about 10% or higher, more preferably at least about 25% or higher, and even more preferably at least about 50% or higher. Furthermore, the magnetic writing may be performed before or after the formation of the servo pattern.
In yet another aspect, the present invention provides a method of servo positioning on a magnetic data storage tape including a magnetic coating on at least one surface of a substrate, a servo pattern comprising a plurality of etched regions in the magnetic coating on the tape, the plurality of etched regions being spaced apart along a length of the tape; and a magnetic signal written over the servo pattern. The method includes detecting electromagnetic modulation in the magnetic coating by passing a magnetic core over the servo pattern and detecting optical modulation by passing an optical read head over the servo pattern. A magnetic read/write head is then positioned based on the electromagnetic and optical modulation detected.
In various embodiments, the electromagnetic modulation and the optical modulation can be detected simultaneously or sequentially. The electromagnetic modulation and the optical modulation may be detected using the same servo pattern or they may be detected using different servo patterns.
These and other features and advantages of the present invention are described more completely below in connection with the illustrated embodiments presented.